Flea infestation of animals is a health and economic concern for pet owners. In particular, the bites of fleas are a problem for animals maintained as pets because the infestation becomes a source of annoyance not only for the pet but also for the pet owner who may find his or her home generally contaminated with insects. Fleas also directly cause a variety of diseases, including allergy, and also carry a variety of infectious agents including, but not limited to, endoparasites (e.g., nematodes, cestodes, trematodes and protozoa), bacteria and viruses. As such, fleas are a problem not only when they are on an animal but also when they are in the general environment of the animal.
The medical importance of flea infestation has prompted the development of reagents capable of controlling flea infestation. Commonly encountered methods to control flea infestation are generally focused on use of insecticides, which are often unsuccessful for one or more of the following reasons: (1) failure of owner compliance (frequent administration is required); (2) behavioral or physiological intolerance of the pet to the pesticide product or means of administration; and (3) the emergence of flea populations resistant to the prescribed dose of pesticide.
Peritrophins, including flea PL1, PL2, PL3, PL4 and PL5 proteins of the present invention, are a family of putative chitin-binding proteins that comprise a structural component of the peritrophic matrix, an acellular membrane composed of proteins and sugars, most commonly chitin which forms a barrier between the contents of an ingested meal and the gut epithelia. Peritrophin-like proteins have also been shown to be present in the trachea of Drosophila embryos, indicating that such proteins may have additional roles outside the midgut. The function of the peritrophin-like proteins in adult fleas is not clear, since adult fleas do not produce a peritrophic matrix in the gut. Peritrophins have been investigated as targets for immunological control of hematophagous insects including the sheep blowfly, Lucilia cuprina. It has been shown in this insect that ingestion of antibodies against peritrophins inhibits the growth of larvae and can result in increased larval mortality. It has also been shown that the ingestion of antibodies against peritrophins reduces the permeability of the peritrophic matrix in L. cuprina larvae. This in turn may inhibit the movement of digested food across the peritrophic matrix to the gut epithelium, resulting in starvation. As such, a flea peritrophin of the present invention represents a novel target for anti-flea vaccines and chemotherapeutic drugs.
Therefore, isolation and sequencing of flea peritrophin genes may be critical for use in identifying specific agents for treating animals for flea infestation.